Upper tube seat of nuclear fuel assembly

Abstract

The invention discloses an upper tube seat of a nuclear fuel assembly. The upper tube seat comprises a seat body, a plurality of quick release assemblies and a cover plate assembly, each quick-release assembly comprises a bottom plate spring, a plurality of acting plate springs and a quick-release positioning piece, the cover plate assembly comprises at least two cover plate pieces, and the at least two cover plate pieces are detachably connected. According to the upper tube base of the nuclear fuel assembly, the quick release assembly and the cover plate assembly are arranged to compensate for the insufficient pressing force, meanwhile, the initial compression amount of a compression spring of a full-reactor-core fuel assembly is reduced, and the bending risk of the fuel assembly caused by the too large pressing force of the fuel assembly can be effectively reduced. Meanwhile, the at least two cover plate parts are arranged and are detachably connected, and the overall height of the upper tube seat of the nuclear fuel assembly can be changed by adjusting the thicknesses of the at least two cover plate parts, so that different pressing force requirements of different fuel assemblies are met, and the upper tube seat is suitable for various types of fuel assemblies.

Description

Technical Field

[0001] The invention relates to the field of reactor nuclear fuel, in particular to an upper tube seat of a nuclear fuel assembly. Background Art

[0002] In existing pressurized water reactors, in order to ensure the compression of the fuel assemblies under different irradiation growth conditions, the initial compression of the compression spring needs to conservatively consider the compression of the fuel assembly with the smallest height (i.e., the new fuel assembly). Therefore, the compression force applied to the fuel assembly at the end of its life is too conservative, which can easily cause the fuel assembly to bend. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide an upper tube seat for a nuclear fuel assembly.

[0004] The technical solution adopted by the present invention to solve the technical problem is: constructing an upper tube seat of a nuclear fuel assembly, which includes a seat body, a plurality of quick-release components and a cover plate assembly;

[0005] Each of the quick-release components comprises a bottom leaf spring, a plurality of action leaf springs and a quick-release positioning piece, wherein the plurality of action leaf springs are stacked and located above the bottom leaf spring, the quick-release positioning piece is passed through the bottom leaf spring and the plurality of action leaf springs, the bottom leaf spring abuts against the upper end surface of the seat body, the lower end of the quick-release positioning piece is clamped under the bottom leaf spring, and the upper end of the quick-release positioning piece is connected to the cover plate component;

[0006] The cover plate assembly comprises at least two cover plate members, and at least two of the cover plate members are detachably connected.

[0007] In some embodiments, a first through hole is formed on the bottom leaf spring, a second through hole corresponding to the first through hole is formed on the action leaf spring, and the quick-release positioning member is passed through the first through hole and the second through hole.

[0008] In some embodiments, a hook portion is provided at one end of the bottom leaf spring away from the first through hole, and a connecting hole is provided at one end of the action leaf spring away from the second through hole, and the hook portion is passed through the connecting hole.

[0009] In some embodiments, the number of the cover plate members is two, and the two cover plate members are divided into a first installation cover plate and a second installation cover plate, and the second installation cover plate is located above the first installation cover plate;

[0010] The first installation cover plate is provided with a first connection hole corresponding to the quick-release positioning member, and the second installation cover plate is provided with a second connection hole corresponding to the first connection hole.

[0011] In some embodiments, the upper tube seat of the nuclear fuel assembly also includes a limit member, a first limit hole is provided on the seat body, a second limit hole corresponding to the first limit hole is provided on the first mounting cover plate, and the two ends of the limit member are respectively connected to the first limit hole and the second limit hole.

[0012] In some embodiments, the base body is provided with a first docking hole, the first mounting cover plate is provided with a second docking hole corresponding to the first docking hole, and the second mounting cover plate is provided with a third docking hole corresponding to the second docking hole.

[0013] In some embodiments, the distance between the lower end surface of the first mounting cover plate and the upper end surface of the second mounting cover plate is 15 mm to 30 mm.

[0014] In some embodiments, the number of the quick-release components is four.

[0015] In some embodiments, the number of the active leaf springs is three.

[0016] In some embodiments, the bottom leaf spring and the plurality of action leaf springs are all bent plate-shaped spring sheets.

[0017] The implementation of the present invention has the following beneficial effects: the upper tube seat of the nuclear fuel assembly compensates for the lack of clamping force by setting a quick-release assembly and a cover plate assembly, while reducing the initial compression of the full core fuel assembly clamping spring, which can effectively reduce the risk of fuel assembly bending caused by excessive fuel assembly clamping force. At the same time, at least two cover plate members are set, and at least two cover plate members are detachably connected. By adjusting the thickness of at least two cover plate members, the overall height of the upper tube seat of the nuclear fuel assembly can be changed, thereby meeting the different clamping force requirements of different fuel assemblies to adapt to various types of fuel assemblies. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solution of the present invention, the present invention will be further described below in conjunction with the accompanying drawings and embodiments. It should be understood that the following drawings only show certain embodiments of the present invention and should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work. In the drawings:

[0019] Figure 1 is a schematic diagram of the application of the upper tube seat of the nuclear fuel assembly in some embodiments of the present invention;

[0020] Figure 2 is a schematic structural diagram of a cover plate assembly in some embodiments of the present invention;

[0021] Figure 3is a schematic diagram of the exploded parts of the upper tube seat of the nuclear fuel assembly in some embodiments of the present invention;

[0022] Figure 4 is a schematic diagram of the overall structure of the upper tube seat of the nuclear fuel assembly in some embodiments of the present invention;

[0023] Figure 5 is a schematic diagram of the structure of a quick-release assembly in some embodiments of the present invention;

[0024] Figure 6 is a schematic structural diagram of a bottom leaf spring in some embodiments of the present invention;

[0025] Figure 7 Schematic diagram of the structure of the active leaf spring in some embodiments of the present invention. DETAILED DESCRIPTION

[0026] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific embodiments of the present invention are now described in detail with reference to the accompanying drawings. In the following description, it should be understood that the directions or positional relationships indicated by "front", "back", "up", "down", "left", "right", "longitudinal", "horizontal", "vertical", "horizontal", "top", "bottom", "inside", "outside", "head", "tail", etc. are based on the directions or positional relationships shown in the accompanying drawings, are constructed and operated in a specific direction, and are only for the convenience of describing the present technical solution, rather than indicating that the device or element referred to must have a specific direction, and therefore cannot be understood as a limitation to the present invention.

[0027] It should also be noted that, unless otherwise clearly specified and limited, the terms such as "installed", "connected", "connected", "fixed", "set" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. When an element is referred to as being "on" or "under" another element, the element can be "directly" or "indirectly" located on the other element, or there may be one or more intermediate elements. The terms "first", "second", "third", etc. are only for the convenience of describing the present technical solution, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second", "third", etc. can explicitly or implicitly include one or more of the features. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0028] See also Figures 1 to 7, is a nuclear fuel assembly upper tube seat in some embodiments of the present invention, which includes a seat body 1, multiple quick-release assemblies 2 and a cover plate assembly 3. Each quick-release assembly 2 includes a bottom leaf spring 21, multiple action leaf springs 22 and a quick-release positioning member 23. The multiple action leaf springs 22 are stacked and located above the bottom leaf spring 21. The quick-release positioning member 23 is penetrated by the bottom leaf spring 21 and the multiple action leaf springs 22. The bottom leaf spring 21 abuts against the upper end surface of the seat body 1. The lower end of the quick-release positioning member 23 is clamped under the bottom leaf spring 21, and the upper end of the quick-release positioning member 23 is connected to the cover plate assembly 3. The cover plate assembly 3 includes at least two cover plate members, and at least two cover plate members are detachably connected. Preferably, the number of the quick-release assemblies 2 is four.

[0029] It can be understood that in a pressurized water reactor reactor, the lower tube seat of the fuel assembly is located on the lower core plate, and the upper core plate is pressed on the fuel assembly clamping system. During operation, due to different neutron injections in different areas, the skeleton growth of fuel assemblies at different positions is different, which leads to differences in the compression of the clamping system, resulting in large differences in the clamping force. Since the growth of the fuel assembly after irradiation is greater than that of the newly added fuel assembly, the quick-release assembly 2 and the cover assembly 3 are installed on the seat body 1 of the upper tube seat of the fuel assembly to compensate for the lack of clamping force, while reducing the initial compression of the full core fuel assembly clamping spring, which can effectively reduce the risk of fuel assembly bending caused by excessive fuel assembly clamping force. At the same time, at least two cover plate members are set, and at least two cover plate members are detachably connected, and the overall height of the upper tube seat of the nuclear fuel assembly can be changed by adjusting the thickness of at least two cover plate members, thereby meeting the different clamping force requirements of different fuel assemblies to adapt to various types of fuel assemblies.

[0030] like Figures 5 to 7 As shown, a first through hole 211 is provided on the bottom leaf spring 21, a second through hole 221 corresponding to the first through hole 211 is provided on the action leaf spring 22, and a quick release positioning member 23 is provided through the first through hole 211 and the second through hole 221. The quick release positioning member 23 can be a bolt member, and the quick release positioning member 23 provides a positioning function for the bottom leaf spring 21 and the action leaf spring 22. In addition, a hook portion 212 is provided at one end of the bottom leaf spring 21 away from the first through hole 211, and a connecting hole 222 is provided at one end of the action leaf spring 22 away from the second through hole 221, and the hook portion 212 is provided through the connecting hole 222. The connecting hole 222 is specifically rectangular, and when the bottom leaf spring 21 and the plurality of action leaf springs 22 are compressed, the hook portion 212 can move in the connecting hole 222, and the arrangement of the hook portion 212 and the connecting hole 222 also provides a positioning function for the bottom leaf spring 21 and the action leaf spring 22. The bottom leaf spring 21 and the plurality of action leaf springs 22 are all bent plate-shaped spring sheets, and the number of the action leaf springs 22 is preferably three.

[0031] In this embodiment, if Figures 2 to 4 As shown, there are two cover plate members, which are divided into a first installation cover plate 31 and a second installation cover plate 32. The second installation cover plate 32 is located above the first installation cover plate 31. The first installation cover plate 31 is provided with a first connection hole 311 corresponding to the quick release positioning member 23, and the second installation cover plate 32 is provided with a second connection hole 321 corresponding to the first connection hole 311. The first connection hole 311 and the second connection hole 321 can both be bolt holes, which are threadedly connected with the quick release positioning member 23 and the first connection hole 311 and the second connection hole 321 to connect the bottom leaf spring 21 and the action leaf spring 22 to the cover plate assembly 3.

[0032] like Figure 3 and Figure 4 As shown, the upper tube seat of the nuclear fuel assembly further includes a stopper 4, a first stopper hole 11 is provided on the seat body 1, a second stopper hole 312 corresponding to the first stopper hole 11 is provided on the first mounting cover plate 31, and two ends of the stopper 4 are respectively connected to the first stopper hole 11 and the second stopper hole 312. The stopper 4 is preferably a stopper pin, which is used to connect the seat body 1 and the first mounting cover plate 31.

[0033] The seat body 1 is provided with a first docking hole 12, the first installation cover plate 31 is provided with a second docking hole 313 corresponding to the first docking hole 12, and the second installation cover plate 32 is provided with a third docking hole 323 corresponding to the second docking hole 313. Positioning pins can be installed in the first docking hole 12, the second docking hole 313 and the third docking hole 323 to complete the relative positioning between the seat body 1, the first installation cover plate 31 and the second installation cover plate 32. The number of the first docking hole 12, the second docking hole 313 and the third docking hole 323 are all two, and the two first docking holes 12, the second docking hole 313 and the third docking hole 323 are respectively arranged diagonally.

[0034] Preferably, the distance between the lower end surface of the first mounting cover plate 31 and the upper end surface of the second mounting cover plate 32 is 15 mm to 30 mm. The distance between the lower end surface of the first mounting cover plate 31 and the upper end surface of the second mounting cover plate 32 is the thickness of the cover plate assembly 3. The thickness of the cover plate assembly 3 can be determined in the following manner: considering the hydraulic force, buoyancy, gravity and design margin to which the fuel assembly is subjected during operation in the stack, the clamping force required to ensure that the fuel assembly does not jump up during operation is calculated. Considering the irradiation relaxation of the clamping spring and the irradiation growth of the fuel assembly, the design thickness of the cover plate assembly 3 can be determined according to the clamping spring force-deformation curve and the clamping force requirement, combined with the distance between the upper and lower core plates and the height of the fuel assembly excluding the cover plate. The number of cover plate parts of the cover plate assembly 3 can be adjusted according to actual conditions and can be two or more.

[0035] It can be understood that the above embodiments only express the preferred implementation modes of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the patent scope of the present invention. It should be pointed out that, for ordinary technicians in this field, without departing from the concept of the present invention, the above technical features can be freely combined, and several deformations and improvements can be made, which all belong to the protection scope of the present invention. Therefore, all equivalent changes and modifications made to the scope of the claims of the present invention should belong to the scope covered by the claims of the present invention.

Claims

1. A nuclear fuel assembly upper tube socket, characterized in that: It comprises a seat body (1), a plurality of quick-release components (2) and a cover plate component (3); Each of the quick-release components (2) comprises a bottom leaf spring (21), a plurality of action leaf springs (22) and a quick-release positioning piece (23); the plurality of action leaf springs (22) are stacked and arranged above the bottom leaf spring (21); the quick-release positioning piece (23) is passed through the bottom leaf spring (21) and the plurality of action leaf springs (22); the bottom leaf spring (21) abuts against the upper end surface of the seat body (1); the lower end of the quick-release positioning piece (23) is clamped below the bottom leaf spring (21); and the upper end of the quick-release positioning piece (23) is connected to the cover plate component (3); The cover plate assembly (3) comprises at least two cover plate components, and at least two of the cover plate components are detachably connected.

2. The nuclear fuel assembly upper tube socket according to claim 1, characterized in that: The bottom leaf spring (21) is provided with a first through hole (211), the action leaf spring (22) is provided with a second through hole (221) corresponding to the first through hole (211), and the quick-release positioning member (23) is passed through the first through hole (211) and the second through hole (221).

3. The nuclear fuel assembly upper tube socket according to claim 2, characterized in that: A hook portion (212) is provided at one end of the bottom leaf spring (21) away from the first through hole (211), and a connecting hole (222) is provided at one end of the action leaf spring (22) away from the second through hole (221), and the hook portion (212) is passed through the connecting hole (222).

4. The nuclear fuel assembly upper tube socket according to claim 1, characterized in that: The number of the cover plate members is two, and the two cover plate members are divided into a first installation cover plate (31) and a second installation cover plate (32), and the second installation cover plate (32) is located above the first installation cover plate (31); The first installation cover plate (31) is provided with a first connection hole (311) corresponding to the quick-release positioning member (23), and the second installation cover plate (32) is provided with a second connection hole (321) corresponding to the first connection hole (311).

5. The nuclear fuel assembly upper tube socket according to claim 4, characterized in that: The nuclear fuel assembly upper tube seat also includes a limiting member (4); the seat body (1) is provided with a first limiting hole (11); the first mounting cover plate (31) is provided with a second limiting hole (312) corresponding to the first limiting hole (11); and the two ends of the limiting member (4) are respectively connected to the first limiting hole (11) and the second limiting hole (312).

6. The nuclear fuel assembly upper tube socket according to claim 4, characterized in that: The seat body (1) is provided with a first docking hole (12), the first installation cover plate (31) is provided with a second docking hole (313) corresponding to the first docking hole (12), and the second installation cover plate (32) is provided with a third docking hole (323) corresponding to the second docking hole (313).

7. The nuclear fuel assembly upper tube socket according to claim 4, characterized in that: The distance between the lower end surface of the first installation cover plate (31) and the upper end surface of the second installation cover plate (32) is 15 mm to 30 mm.

8. The nuclear fuel assembly upper tube socket according to claim 1, characterized in that: The number of the quick-release components (2) is four.

9. The nuclear fuel assembly upper tube socket according to claim 1, characterized in that: The number of the action leaf springs (22) is three.

10. The nuclear fuel assembly upper tube socket according to claim 1, characterized in that: The bottom leaf spring (21) and the plurality of action leaf springs (22) are all bent plate-shaped spring leaves.

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